Electrode assembly and electrochemical cell including the same

ABSTRACT

An electrode assembly according to the present disclosure includes an electrode stack part formed by stacking at least one radical unit having a four-layered structure of a first electrode, a separator, a second electrode and a separator, and an electrode fixing part for wrapping and fixing the electrode stack part. The electrode assembly according to the present disclosure may be fabricated by means of a stacking process other than a folding process, and may accomplish accurate alignment and stable fixing.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a Continuation of PCT International Application No.PCT/KR2013/005760 filed on Jun. 28, 2013, which claims priority under 35U.S.C. § 119(a) to Patent Application Nos. 10-2012-0069832 filed in theRepublic of Korea on Jun. 28, 2012 and to 10-2013-0075040 filed in theRepublic of Korea on Jun. 28, 2013, all of which are hereby expresslyincorporated by reference into the present application.

BACKGROUND OF THE INVENTION

Field of the Invention

The present disclosure relates to an electrode assembly and anelectrochemical cell including the same, and more particularly to anelectrode assembly fabricated by a stacking method other than a foldingmethod and accomplishing minute alignment and stable fixing, and anelectrochemical cell including the same.

Description of the Related Art

Secondary batteries may be classified into various types according tothe structure of electrode assemblies. For example, the secondarybatteries may be classified into a stack type structure, a wrapping type(jelly-roll type) structure or a stack/folding type structure. For thestack type structure, a cathode, a separator, and an anode are cut intoa certain size and then are stacked one by one to form an electrodeassembly. In this case, the separator is disposed between the cathodeand the anode. For the wrapping type structure, a cathode, a separator,an anode and a separator are formed into sheet shapes, stacked one byone, and then wrapped to form an electrode assembly. For thestack/folding type structure, a full cell or a bicell is formed first,and is wrapped by using a separator sheet to form an electrode assembly.After cutting the cathode, the separator and the anode into a certainsize and stacking thereof one by one, the full cell or the bicell may beformed. (The full cell or the bicell respectively includes one or morecathodes, separators and anodes.) The structure of the stack/foldingtype is disclosed in more detail in Patent Literatures 1 and 2.

However, since the electrode units (cathode, separator and anode)constituting the electrode assembly are stacked separately, the minutealignment of the electrode assembly is very difficult. In addition, alarge number of processes are necessary to produce the electrodeassembly. In general, for the manufacture of the stack/folding typestructure, two lamination apparatuses and one folding apparatus arenecessary. Thus, the fabricating process of the electrode assembly isvery complicated. Particularly, since the full cells or the bicells arestacked through folding in the stack/folding type structure, the minutealignment of the full cells or the bicells is very difficult.

-   (Patent Literature 1) Korean Publication Patent No. 2001-0082059-   (Patent Literature 2) Korean Publication Patent No. 2001-0082060

SUMMARY OF THE INVENTION

An aspect of the present disclosure considering the above-describeddefects provides an electrode assembly fabricated by a stacking methodother than a folding method and accomplishing minute alignment andstable fixing, and an electrochemical cell including the same.

According to an aspect of the present disclosure, there is provided anelectrode assembly including an electrode stack part formed by stackingat least one radical unit having a four-layered structure of a firstelectrode, a separator, a second electrode and the separator, and anelectrode fixing part for wrapping and fixing the electrode stack part.In this case, the radical unit may have an eight-layer structure byrepeatedly stacking the four-layered structure.

More particularly, the radical unit may include a bicell formed bystacking the first electrode, the separator, the second electrode, theseparator and the first electrode one by one, and a supplementary cellformed by stacking the separator, the second electrode and the separatorone by one from one of the first electrode among the two of the firstelectrodes.

In addition, the radical unit may include a bicell formed by stackingthe first electrode, the separator, the second electrode, the separatorand the first electrode one by one, a separator stacked on one of thefirst electrode among the two of the first electrodes, and asupplementary cell formed by staking the separator and the secondelectrode one by one from one of the other first electrode among the twoof the first electrodes.

According to the electrode assembly of the present disclosure, radicalunits are repeatedly stacked to form an electrode stack part. Thus, theelectrode assembly may be formed by means of a stacking process otherthan a folding process, and the productivity of the electrode assemblymay be improved.

In addition, in the electrode assembly of the present disclosure, theelectrode assembly may be aligned on the whole by aligning the radicalunits, and minute alignment of the electrode assembly may be possible.

Further, the electrode stack part of the electrode assembly according tothe present disclosure may be fixed through wrapping an electrode fixingpart. Thus, a stable fixing may be accomplished.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, features and other advantages of thepresent disclosure will be more clearly understood from the followingdetailed description taken in conjunction with the accompanyingdrawings, in which:

FIG. 1 is a side view illustrating an electrode stack part according tothe present disclosure;

FIG. 2 is a side view illustrating a first structure of a radical unitaccording to the present disclosure;

FIG. 3 is a side view illustrating a second structure of a radical unitaccording to the present disclosure;

FIG. 4 is a process diagram illustrating a manufacturing process of theradical unit in FIG. 2;

FIG. 5 is a side view illustrating a third structure of a radical unitaccording to the present disclosure;

FIG. 6 is an exploded perspective view illustrating the radical unit inFIG. 5;

FIG. 7 is a process diagram illustrating a manufacturing process of theradical unit in FIG. 5;

FIG. 8 is a side view illustrating a fourth structure of a radical unitaccording to the present disclosure;

FIG. 9 is an exploded perspective view illustrating the radical unit inFIG. 8;

FIG. 10 is a process diagram illustrating a manufacturing process of theradical unit in FIG. 8;

FIG. 11 is a perspective view illustrating the First Embodiment of anelectrode fixing part according to the present disclosure;

FIG. 12 is a perspective view illustrating the Second Embodiment of anelectrode fixing part according to the present disclosure;

FIG. 13 is a perspective view illustrating the Third Embodiment of anelectrode fixing part according to the present disclosure;

FIG. 14 is a perspective view illustrating the Fourth Embodiment of anelectrode fixing part according to the present disclosure;

FIG. 15 is a perspective view illustrating the Fifth Embodiment of anelectrode fixing part according to the present disclosure; and

FIG. 16 is a perspective view illustrating the Sixth Embodiment of anelectrode fixing part according to the present disclosure.

DETAILED DESCRIPTION OF THE PREFERRED EMBODINENT

Exemplary embodiments of the present disclosure will now be described indetail with reference to the accompanying drawings. However, the presentdisclosure is not limited or restricted to the following exemplaryembodiments.

The electrode assembly according to the present disclosure basicallyincludes an electrode stack part and an electrode fixing part. First,the electrode stack part will be explained. The electrode stack part(see reference numeral 100 a, etc. in FIG. 1) includes at least oneradical unit (see 110 a, etc. in FIG. 2). That is, the electrode stackpart 100 may be formed by including one radical unit 110 or at least tworadical units 110. The electrode stack part 100 may be formed bystacking the radical units 110. For example, the electrode stack part100 a may be formed by stacking one radical unit 110 a and anotherradical unit, as illustrated in FIG. 1. As described above, theelectrode stack part 100 may be formed by stacking the radical units110. That is, the radical units 110 may be formed in advance, and thenstacked one by one to form the electrode stack part 100.

As described above, the electrode stack part 100 according to thepresent disclosure is characterized in that the electrode stack part 100is formed by repeatedly stacking the radical units 110. Throughmanufacturing the electrode stack part 100 according to the method, theradical units 110 may be precisely aligned, and the productivity may beimproved. (For example, a folding process applied in the stack/foldingtype electrode may be omitted).

The radical unit 100 is formed by stacking a first electrode 111, aseparator 112, a second electrode 113 and the separator 112. Asdescribed above, the radical unit 110 has a basically four-layeredstructure. More particularly, the radical unit 110 may be obtained bystacking the first electrode 111, the separator 112, the secondelectrode 113 and the separator 112 one by one from the upper portion tothe lower portion, as illustrated in FIG. 2, or by stacking the firstelectrode 111, the separator 112, the second electrode 113 and theseparator 112 one by one from the lower portion to the upper portion, asillustrated in FIG. 3. In this case, the first electrode 111 and thesecond electrode 112 may be opposite electrodes from each other. Forexample, when the first electrode 111 is an anode, the second electrode113 may be a cathode. Of course, the electrodes may have inversepolarity.

For reference, when the radical units are repeatedly stacked to form theelectrode stack part, the first electrode may be positioned at theuppermost portion or the lowermost portion of the electrode stack part.In this case, to avoid direct contact of the first electrode with a casesuch as a pouch, the separator may be additionally stacked on the firstelectrode positioned at the outermost portion to insulate the firstelectrode positioned at the outermost portion and exposed to exterior(for example, the first electrode positioned at the uppermost portion inFIG. 1) from the case. A separator sheet may also be applied instead ofthe separator. For example, the electrode stack part may be wrapped withthe separator sheet to insulate the first electrode positioned at theoutermost portion from the case. Alternatively, the first electrodepositioned at the outermost portion may be insulated from the case bymeans of an electrode fixing part, which will be described herein below.

The radical unit 110 a may be formed by the following process (see FIG.4). First, a first electrode material 121, a first separator material122, a second electrode material 123 and a second separator material 124are prepared. In this case, the electrode materials 121 and 123 may becut into a certain size to form the electrodes 111 and 113. The sameprocess is conducted for the first and second separator materials 122and 124. To automate the manufacturing process, the electrode materialand the separator material may have a wrapped shape on a roll. Afterpreparing the materials, the first electrode material 121 is cut into acertain size through a cutter C₁. Then, the second electrode material123 is also cut into a certain size through a cutter C₂. After that, thefirst electrode material 121 having the certain size is supplied on thefirst separator material 122. The second electrode material 123 havingthe certain size is also supplied on the second separator material 124.Then, all of the materials are supplied to laminators L₁ and L₂.

The electrode stack part 100 may be formed by repeatedly stacking theradical units 110 as described above. However, when the electrode andthe separator constituting the radical unit 110 are separated from eachother, the repetitive stacking of the radical units 110 may bedifficult. Thus, the electrode and the separator may be attached to eachother when forming the radical unit 110. The laminators L₁ and L₂ areused to attach the electrode and the separator to each other. That is,the electrode material and the separator material are attached to eachother by applying a pressure or a heat and pressure onto the materialsby the laminators L₁ and L₂. Through the attachment, the radical unit110 may maintain the shape thereof more stably.

Then, the first separator material 122 and the second separator material124 are cut into a certain size through a cutter C₃. By conducting thecutting, the radical unit 110 a may be formed. Various kinds ofinspections on the radical unit 110 a may be additionally conducted asoccasion demands. For example, inspections such as a thicknessinspection, a vision inspection, a short inspection, and the like may beadditionally conducted.

Meanwhile, the surface of the separator (the separator material) may becoated with a coating material having adhesiveness. The coating materialmay be a mixture of inorganic particles and a binder polymer. (Thecoating by using the coating material is called an SRS coating.) Theinorganic particles may improve the thermal stability of the separator.That is, the inorganic particles may prevent the contraction of theseparator at a high temperature. In addition, the binder polymer may fixthe inorganic particles. Thus, the inorganic particles may have acertain porous structure. Due to the porous structure, ions may easilymove from the cathode to the anode even though the separator is coatedwith the inorganic particles. In addition, the binder polymer maymaintain the inorganic particles on the separator stably to improve themechanical stability of the separator. In addition, the binder polymermay attach the separator onto the electrode more stably. For reference,the separator may be formed by using a polyolefin-based separator base.

As illustrated in detail in FIGS. 2 and 3, the electrodes 111 and 113are positioned at both sides of the separator 112, however, theelectrode 113 is positioned only at one side of the other separator 112.Thus, the coating material may be coated on both sides of the separator112, while the coating material may be coated only on one side of theother separator 112. That is, the coating material may be coated on bothsides of the separator 112 facing the first electrode 111 and the secondelectrode 113, and the coating material may be coated on one side of theother separator 112 facing the second electrode 113.

As described above, the attachment within the radical unit by means ofthe coating material may be sufficient. Thus, the coating may beconducted only on one side of the separator 112 as described above.Since the radical units may be attached to each other by means of a heatpress method, etc., the coating may be conducted on both sides of theseparator 112 as occasion demands. That is, the separator 112 may becoated on one side facing the second electrode 113 and on the oppositeside thereof as occasion demands.

For reference, when a coating material having the adhesiveness is coatedon the separator, a direct pressurization onto the separator by using acertain object is not preferred. Generally, the separator is extendedlengthily and outward from the electrode. Thus, the terminal of theseparator 112 and the terminal of another separator 112 may be combinedto each other. For example, the terminal of the separator 112 and theterminal of another separator 112 may be welded to each other by meansof an ultrasonic welding. In this case, a direct pressurization on anobject using a horn is necessary for conducting the ultrasonic welding.However, the horn may attach to the separator due to the coatingmaterial having the adhesiveness when the terminal portion of theseparator is directly pressurized by means of the horn. In this case,the apparatus may be out of order. Therefore, the direct pressurizationonto the separator by using a certain object is not preferable when thecoating material having the adhesiveness is coated on the separator.

Additionally, the radical unit 110 does not necessarily have afour-layered structure. For example, the radical unit 110 may have aneight-layered structure obtained by stacking the first electrode 111,the separator 112, the second electrode 113, the separator 112, thefirst electrode 111, the separator 112, the second electrode 113 and theseparator 112 one by one. That is, the radical unit 110 may be formed asthe eight-layered structure by repeating the four-layered structures.

Exemplary embodiments will be described in more detail. As illustratedin FIGS. 5 and 6, the radical unit 110 c may form an eight-layeredstructure including a bicell 116 and a supplementary cell 117. In thiscase, the bicell 116 is formed by stacking the first electrode 111, theseparator 112, the second electrode 113, the separator 112 and the firstelectrode 111 one by one from the upper portion to the lower portion (orfrom the lower portion to the upper portion). In general, when the firstelectrode is a cathode, the thus obtained structure may be called anA-type bicell, and when the first electrode is an anode, the thusobtained structure may be called a C-type bicell.

The supplementary cell 117 may be formed by stacking the separator 112,the second electrode 113 and the separator 112 one by one from the firstelectrode 111 of the bicell 116, that is, subsequently from the firstelectrode 111 of the bicell 116 to outward. In this case, the firstelectrode 111 of the bicell 116 may be the first electrode 111positioned at the uppermost portion of the bicell 116, or the firstelectrode 111 positioned at the lowermost portion of the bicell 116.(FIG. 5 illustrates an example embodiment in which the supplementarycell is stacked on the first electrode positioned at the lowermostportion of the bicell.)

As described above, the electrode stack part 100 may be formed byrepeatedly stacking the radical units 110 c having the above-describedeight-layered structure. (Of course, the electrode stack part may beformed by using only one radical unit.) Through forming the radical unit110 c as described above, the electrode stack part 100 may be formedonly by means of the stack process other than the folding process whileusing one of the A-type bicell or the C-type bicell applied in thestack/folding structure.

The radical unit 110 c having the eight-layered structure as describedabove may be formed by the following process (see FIG. 7). First, afirst electrode material, a separator material, a second electrodematerial, a separator material and a first electrode material areprepared. Then, these materials are stacked one by one and supplied tofirst laminators L₁ and L₂. In the first laminators L₁ and L₂, thematerials are laminated into a corresponding structure of the bicell116. (The laminating process is the same as the common laminatingprocess.) After that, the separator material, the second electrodematerial and the separator material are additionally supplied to secondlaminators L₃ and L₄. In the second laminators L₃ and L₄, the materialsare laminated into a corresponding structure of the radical unit 110 c.

Through forming the radical unit 110 c by conducting the above describedprocesses, the common processes may be applied. Thus, the electrodeassembly may be fabricated by introducing a new process without afolding process, and the cost consumed for equipment investment may beremarkably decreased. In addition, since the radical unit 110 c may beformed by conducting one continuous laminating process, the process maybe simplified. Particularly, the second laminating process may beconducted at a lower temperature and under a lower pressure whencompared with the first laminating process, the cost may be decreased.Further, the second laminating process may be conducted by laminatingthe supplementary cell 117 on one side of the bicell 116. Thus, theupper part L; and the lower part L₄ of the second laminator may beoperated at different temperatures. Therefore, the power consumption ofthe second laminator may be decreased.

In addition, the radical unit 110 d may have an eight-layered structureas illustrated in FIGS. 8 and 9. That is, as illustrated in FIG. 8, theradical unit 110 d may be formed as an eight-layered structure includingthe bicell 116 formed by stacking the first electrode 111, the separator112, the second electrode 113, the separator 112 and the first electrode111 one by one, and the supplementary cell 118 formed by stacking theseparator 112 stacked on one of the two first electrodes 111, and theseparator 112 and the second electrode 113 stacked on the other one ofthe two first electrodes 111 one by one. FIG. 8 illustrates an exampleembodiment in which the separator 112 is stacked on the first electrode111 positioned at the uppermost portion of the bicell 116, and thesupplementary cell 118 is stacked on the first electrode 111 positionedat the lowermost portion of the bicell 116. However, the stacking may beconducted inversely.

The above-described radical unit 110 d having the eight-layeredstructure may be formed by the following process (see FIG. 10). First,the first electrode material, the separator material, the secondelectrode material, the separator material and the first electrodematerial are prepared. Then, these materials are stacked one by one andsupplied to the first laminators L₁ and L₂. In the first laminators L₁and L₂, the materials are laminated into a corresponding structure tothe bicell 116. (The laminating process is the same as the commonlaminating process.) Subsequently after that, the materials are suppliedto the second laminators L_and L₄ so that the separator 112 may bestacked on the first electrode 111 positioned at the uppermost portion,and so that the separator 112 and the second electrode 113 are stackedone by one from the first electrode 111 positioned at the lowermostportion of the bicell 116 to the outward. In the second laminators L₃and L₄, the materials are laminated into a corresponding structure tothe radical unit 110 d. For reference, the laminating process of theseparator 112 on the first electrode 111 positioned at the uppermostportion, and the laminating process of the separator 112 and the secondelectrode 113 one by one from the first electrode 111 positioned at thelowermost portion of the bicell 116 to the outward may be conducted inseparate laminators.

Following the electrode stack part 100, the electrode fixing part 200will be explained. As described above, the electrode assembly accordingto the present disclosure is basically characterized in that theelectrode stack part 100 is formed only by a stack process other than afolding process. That is, according to the present disclosure, theradical unit 110 is formed by the laminating process, and then, one ormore of the radical units 100 are stacked to form the electrode stackpart 100. In order to fix the electrode stack part 100 more stably, theelectrode assembly according to the present disclosure includes anelectrode fixing part 200 for wrapping and fixing the electrode stackpart 100. The electrode fixing part 200 may be accomplished in variousembodiments as described herein below.

First, the electrode fixing part 200 may include an upper fixing member211 provided at the upper portion of the electrode stack part 100, and alower fixing member 212 provided at the lower portion of the electrodestack part 100, as illustrated in FIG. 11. Here, the lower fixing member212 may be connected with the upper fixing member 211 to fit closely theelectrode stack part 100 along with the upper fixing member 211. Throughthe fit, the electrode fixing part 200 a may fix the electrode stackpart 100. That is, the electrode stack part 100 may be fixed by anelectrode fixing part 200 a by positioning the electrode stack part 100between the upper fixing member 211 and the lower fixing member 212, andattaching the upper fixing member 211 and the lower fixing member 212 toeach other.

In this case, the lower fixing member 212 may be attached to the upperfixing member 211 by means of an ultrasonic welding or a heat sealing.Through the attachment, a closing part 216 may be formed at theattaching part of the upper fixing member 211 and the lower fixingmember 212. The closing part 216 may be formed at both sides. Here, theclosing part 216 may have a width (d) of about 1 to 5 mm. When theultrasonic welding is applied, welding strength may be about 30 to 100gf. In addition, when the heat sealing is applied, a sealing temperaturemay be from about 120° C. to 180° C., a sealing thickness may be about50% to 80% of an original material, and a sealing strength may be about30 to 100 gf.

Alternatively, an electrode fixing part 200 b may be a fixing sheet 221having a sheet shape and formed to wrap the electrode stack part 100, asillustrated in FIG. 12. In this case, one terminal and the otherterminal of the fixing sheet may be connected to each other by means ofthe ultrasonic welding or the heat sealing to wrap the electrode stackpart 100. That is, the electrode stack part 100 may be wrapped whilemaking one round, by using the fixing sheet 221, and the one terminaland the other terminal of the fixing sheet 221 contacting to each othermay be connected. Then, the electrode stack part 100 may be fixed by theelectrode fixing part 200 b.

For reference, the electrode fixing part 200 may be formed by using adifferent material from the separator 112, for example, by using atleast one of a non-woven fabric, PP, PE, and PET. More particularly, theelectrode fixing part 200 may be formed by using a non-woven fabrichaving a pore size of about 1 μm over. Alternatively, the electrodefixing part 200 may be formed by using at least one of the PP, the PEand the PET having a thickness of about 20 to 100 μm.

In addition, an electrode fixing part 200 c may have a tube shapeincluding a first opening 231, a second opening facing the first opening231, and an inner space extended from the first opening 231 to thesecond opening for receiving the electrode stack part 100, asillustrated in FIG. 13. The electrode fixing part 200 c as describedabove may closely fit the electrode stack part 100 by the contractiondue to heat. That is, by receiving the electrode stack part 100 in theinner space of the electrode fixing part 200 c and by heating theelectrode fixing part 200 c, the electrode fixing part 200 c may becontracted and closely fit the electrode stack part 100. Through thefit, the electrode fixing part 200 c may fix the electrode stack part100.

An electrode fixing part 200 d may be formed as a porous insulatingtape, as illustrated in FIG. 14. That is, the electrode stack part 100may be fixed by wrapping the electrode stack part 100 using the porousinsulating tape.

Finally, an electrode fixing part 200 e may be extended from the uppersurface of the electrode stack part 100 along the side surface of theelectrode stack part 100 to the lower surface of the electrode stackpart 100 to fix the electrode stack part 100, as illustrated in FIG. 15.For example, an end portion of a polymer tape is fixed to the uppersurface of the electrode stack part 100. Then, the other end portion ofthe polymer tape is drawn along the side surface of the electrode stackpart 100 and is fixed to the lower surface of the electrode stack part100. In this case, the electrode stack part 100 may be fixed by means ofthe polymer tape through a heat welding. In addition, as illustrated inFIG. 16, the electrode fixing part 200 f may wrap the electrode stackpart 100 by at least one round. As described above, the electrode fixingpart may not completely wrap the electrode stack part.

Hereinafter, the electrode assembly according to the present disclosurewill be explained.

Cathode Structure

A radical unit basically includes a cathode and an anode. In addition,the radical unit includes a separator between the cathode and the anode.The cathode may be manufactured, for example, by coating a mixture of acathode active material, a conductive material and a mixture of a binder(slurry) on a cathode current collector, drying and pressing. Themixture may further include a filler as occasion demands. The cathodemay be formed as a sheet shape and installed on a roll.

[Cathode Current Collector]

A cathode current collector is generally manufactured to a thickness ofabout 3 to 500 μm. For the cathode current collector, a material notinducing the chemical change and having a high conductivity may be used.For example, stainless steel, aluminum, nickel, titanium, clacinedcarbon, a surface treated material of aluminum or stainless steel withcarbon, nickel, titanium, silver, or the like may be typically used.However, the present disclosure may not be limited thereto. To increasethe adhesiveness of a cathode active material, minute embossing may beformed on the surface of the cathode current collector. In addition, thecathode current collector may have various shapes such as a film, asheet, a foil, a net, a porous body, a foamed body, a non-woven fabric,and the like.

[Cathode Active Material]

A cathode active material for a lithium secondary battery may include,for example, a layered compound of lithium cobalt oxide (LiCoO₂),lithium nickel oxide (LiNiO₂), etc. or a substituted compound with oneor more transition metals; lithium manganese oxide such asLi_(1+x)Mn_(2−x)O₄ (in which x is 0 to 0.33), LiMnO₃, LiMn₂O₃, LiMnO₂,etc.; lithium copper oxide (Li₂CuO₂); vanadium oxide such as LiV₃O₈,LiFe₃O₄, V₂O₅, Cu_(Z)V₂O₇, etc.; Ni site-type lithium nickel oxiderepresented by Chemical Formula of LiNi_(1−x)M_(x)O₂ (in which, M=Co,Mn, Al, Cu, Fe, Mg, B or Ga, x=0.01 to 0.3); lithium manganese complexoxide represented by Chemical Formula LiMn_(2−x)M_(x)O₂ (in which M=Co,Ni, Fe, Cr, Zn or Ta, and x=0.01 to 0.1) or Li₂Mn₃MO₈ (in which, M=Fe,Co, Ni, Cu or Zn); LiMn₂O₄ in which a portion of Li is substituted withalkaline earth metal ions; a disulfide compound; Fe₂ (MoO₄)₃, and thelike. However, the present disclosure may not be limited thereof.

Generally, a conductive material is added into a mixture including thecathode active material by 1 to 50 wt % based on the total amount of themixture. The conductive material may be formed by using a materialhaving conductivity without inducing chemical change. For example,graphite such as natural graphite, synthetic graphite, etc.; carbonblack such as carbon black, acetylene black, ketjen black, channelblack, furnace black, lamp black, thermal black, etc.; conductive fibersuch as carbon fiber, metal fiber, etc.; a metal powder such as a carbonfluoride powder, an aluminum powder, a nickel powder, etc.; conductivewhisker such as potassium titanate, etc.; conductive metal oxide such astitanium oxide, etc.; a conductive material such as polyphenylenederivatives, etc. may be typically used.

A binder is a component assisting the bonding of the active materialwith the conductive material and the bonding with the current collector,and is commonly included by about 1 to 50 wt % based on the total amountof the mixture including the cathode active material. Typical examplesof the binder may include polyfluoro vinylidene, polyvinyl alcohol,carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose,regenerated cellulose, polyvinyl pyrrolidone, tetrafluoroethylene,polyethylene, polypropylene, ethylene-propylene-diene polymer (EPDM),sulfonated EPDM, styrene butadiene rubber, fluorine rubber, variouscopolymers, etc.

A filler is a component restraining the expansion of the cathode and maybe selectively used. A material not inducing chemical change and havinga fiber phase may be used without limitation. For example, anolefin-based polymer such as polyethylene, polypropylene, and the like;fiber phase material such as glass fiber, carbon fiber, and the like maybe used.

Anode Structure

An anode may be manufactured by coating an anode current collector withan anode active material, drying and pressing. A conductive material, abinder, a filler, etc. may be selectively included as occasion demands.The anode may be formed as a sheet shape and may be installed on a roll.

[Anode Current Collector]

An anode current collector is generally manufactured to a thickness ofabout 3 to 500 μm. For the anode current collector, a material notinducing chemical change and having conductivity may be used. Forexample, copper, stainless steel, aluminum, nickel, titanium, clacinedcarbon, a surface treated material of copper or stainless steel withcarbon, nickel, titanium, silver, an aluminum-cadmium alloy, etc. may beused. Also, to increase the adhesiveness of the anode active material,minute embossing may be formed on the surface of the anode currentcollector. The anode current collector may have various shapes such as afilm, a sheet, a foil, a net, a porous body, a foamed body, a non-wovenfabric, etc.

[Anode Active Material]

An anode active material may include, for example, carbon such asnon-graphitizable carbon, graphite-based carbon, etc.; a metal complexoxide such as Li_(x)Fe₂O₃ (0≦x≦1), Li_(x)WO₂ (0≦x≦1),Sn_(x)Me_(1−x)Me′_(y)O_(z) (Me: Mn, Fe, Pb, Ge; Me′: Al, B, P, Si,elements found in Group 1, Group 2 and Group 3 in a periodic table,halogen; 0≦x≦1; 1≦y≦3; 1≦z≦8), etc.; a lithium metal; a lithium alloy; asilicon-based alloy; a tin-based alloy; a metal oxide such as SnO, SnO₂,PbO, PbO₂, Pb₂O₃, Pb₃O₄, Sb₂O₃, Sb₂O₄, Sb₂O₅, GeO, GeO₂, Bi₂O₃, Bi₂O₄,Bi₂O₅, etc.; a conductive polymer such as polyacetylene, etc.;Li—Co—Ni-based material, etc.

Separator Structure

A separator (a separator sheet) may be melt by the pressure, or the heatand pressure of a laminator to be attached onto the cathode or theanode. When the pressure is applied from the laminator, the electrodeand the separator (the separator sheet) may make a stable interfacecontact. (Further, the contact may be accomplished separately throughthe above-described SRS coating.)

The separator (the separator sheet) may have insulating properties. Inaddition, the separator may have a porous structure for the movement ofions. Generally, the separator may have the pore diameter of from about0.01 to 10 μm. The thickness of the separator may be generally about 5to 300 μm. The separator may be formed into a thin film having high iontransmittance, high mechanical strength and high insulating properties.For example, the separator (the separator sheet) may be an olefin-basedpolymer such as chemical-resistant and hydrophobic polypropylene, etc; asheet or a non-woven fabric formed by using glass fiber or polyethylene,etc.

When a solid electrolyte such as a polymer is used as an electrolyte,the solid electrolyte may also function as the separator. For example, apolyethylene film, a polypropylene film, or a multi-layered filmobtained by combining the films, or a polymer film for a polymerelectrolyte or a gel-type polymer electrolyte such as polyvinylidenefluoride, polyethylene oxide, polyacrylonitrile, or polyvinylidenefluoride hexafluoropropylene copolymer, may be used.

Hereinafter, an electrochemical device in which the electrode assemblyaccording to the present disclosure may be applicable, will beexplained.

The electrode assembly according to the present disclosure may beapplied in an electrochemical cell producing electricity through theelectrochemical reaction of a cathode and an anode. Typical examples ofthe electrochemical cell include a super capacitor, an ultra capacitor,a secondary battery, a fuel battery, an apparatus for electrolysis, anelectrochemical reactor, and the like. The electrode assembly accordingto the present disclosure may be particularly and preferably applied inthe secondary battery (for example, lithium secondary battery).

A lithium secondary battery is used as a power source of a medium andlarge size device as well as a small size device. When the lithiumsecondary battery is used as the power source of the medium and largesize device, a battery module may be preferably formed by using thesecondary battery according to the present disclosure as one unitbattery. A battery pack including the battery module may be used as apower source in a power tool; an electric vehicle selected from thegroup consisting of an electric vehicle (EV), a hybrid electric vehicle(HEV), and a plug-in hybrid electric vehicle (PHEV); an E-bike; anE-scooter; an electric golf cart; an electric truck; an electriccommercial vehicle, and the like.

While the present disclosure has been shown and described in connectionwith the exemplary embodiments, it will be apparent to those skilled inthe art that modifications and variations can be made without departingfrom the spirit and scope of the invention as defined by the appendedclaims.

INDUSTRIAL APPLICABILITY

The present disclosure relates to an electrode assembly fabricated by astacking method other than a folding method and accomplishing minutealignment and stable fixing, and an electrochemical cell including thesame, so that the present disclosure has industrial applicability.

What is claimed is:
 1. An electrode assembly comprising: an electrodestack part obtained by stacking at least two radical units having arepeating four-layered structure of a first electrode, a firstseparator, a second electrode and a second separator; and an electrodefixing part for wrapping and fixing the electrode stack part, whereineach of the radical units have an eight-layered structure by repeatedlystacking the four-layered structures, wherein the radical units include:a bicell formed by stacking the first electrode, the first separator,the second electrode, the second separator and the first electrode oneby one; and a supplementary cell formed by stacking a third separator,the second electrode and a fourth separator one by one from one of thefirst electrodes among the two of the first electrodes, or wherein theradical units include: a bicell formed by stacking the first electrode,the first separator, the second electrode, the second separator and thefirst electrode one by one; a third separator stacked on one of thefirst electrodes among the two of the first electrodes; and asupplementary cell formed by stacking a fourth separator and the secondelectrode one by one from the other of the first electrodes among thetwo of the first electrodes, wherein the separators of the radical unitshaving electrodes on both sides of the separators facing the separatorare coated with coating material on the both sides of the separators toattach the separators to the facing electrodes, and wherein theseparators of the radical units having one electrode on only one side ofthe separators are coated with coating material on only the one side ofthe separators to attach the separators to the facing electrodes on theone side of the separators, and are uncoated with coating material onthe other side of the separators, and wherein the at least two radicalunits comprise a first radical unit and a second radical unit, andwherein the stack part comprises a junction where the first radical unitcontacts the second radical unit and at the junction the uncoated sideof at least one separator of the first radical unit is placed in directcontact with an electrode of the second radical unit.
 2. The electrodeassembly of claim 1, wherein the attachment of the first electrode andthe first separator or the attachment of the second electrode and thesecond separator is an attachment through applying a pressure onto thecorresponding electrode and the corresponding separator, or anattachment through applying a pressure and heat onto the correspondingelectrode and the corresponding separator.
 3. The electrode assembly ofclaim 1, wherein a surface of the first separator is coated with acoating material having adhesiveness.
 4. The electrode assembly of claim3, wherein the coating material is a mixture of inorganic particles anda binder polymer.
 5. The electrode assembly of claim 1, wherein theelectrode fixing part comprises an upper fixing member provided on anupper portion of the electrode stack part, and a lower fixing memberprovided under the electrode stack part, the lower fixing member beingconnected with the upper fixing member, the lower fixing member and theupper fixing member closely fitting the electrode stack part.
 6. Theelectrode assembly of claim 5, wherein the lower fixing member isattached to the upper fixing member by means of an ultrasonic welding ora heat sealing.
 7. The electrode assembly of claim 1, wherein theelectrode fixing part is obtained by wrapping the electrode stack partwith a fixing sheet having a sheet shape.
 8. The electrode assembly ofclaim 7, wherein one terminal side and another terminal side of thefixing sheet are attached to each other by means of an ultrasonicwelding or a heat sealing to wrap the electrode stack part.
 9. Theelectrode assembly of claim 1, wherein the electrode fixing part has atube shape providing a first opening, a second opening facing the firstopening, and an inner space extended from the first opening to thesecond opening for receiving the electrode stack part.
 10. The electrodeassembly of claim 9, wherein the electrode fixing part fits theelectrode stack part by a contraction due to heat.
 11. The electrodeassembly of claim 1, wherein the electrode fixing part is extended froman upper surface of the electrode stack part along a side surface of theelectrode stack part to a lower surface of the electrode stack part tofix the electrode stack part.
 12. The electrode assembly of claim 11,wherein the electrode fixing part wraps the electrode stack part by atleast one round.